Abstract:

Serious accidents will be caused by the leakage of supercritical CO₂ pipelines. Leakage experiments on small leakage diameters for pure supercritical CO₂ and CO₂ pipeline containing impurities were performed with a small scale (14.85m long, 15mm id) laboratory apparatus. The pressure and temperature responses and the characteristics of phase transitions during the leakage were studied with various leakage diameters and initial inner pressures. The results show that the temperature inside the pipeline reached a minima during the leakage of supercritical CO₂ pipeline and the CO₂ fluid transferred directly from the supercritical state to the gaseous state. Besides, the leakage time and the minimum temperature of the medium in the pipe decreased with the increasing of leakage sizes. The addition of N₂ shortened the whole leakage time and also increased the minimum temperature. The higher N₂ added, the higher the minimum temperature was. Furthermore, based on the self-preservation of leakage time for supercritical CO₂ pipeline, empirical formulas for the pressure responses inside the pipeline were obtainedunder different leakage nozzle diameters and initial inner pressures.under different leakage nozzle diameters and initial inner pressures.

Key words: pipeline leakage, supercritical carbon dioxide, pressure response, minimum temperature, impurity

摘要：

超临界CO₂管道运行过程中一旦发生泄漏，将会造成严重的事故。本文基于小尺度CO₂管道（长14.85m，内径15mm）实验装置开展了超临界纯CO₂及含杂质超临界CO₂管道的小孔泄漏实验，测量了不同泄漏孔径及不同起始压力条件下超临界CO₂管道泄漏过程中管内介质的压力和温度响应曲线，分析了管道泄漏过程中CO₂的相态变化。研究结果表明，在超临界CO₂管道泄漏过程中，管内流体温度存在一个最低值，CO₂由超临界态直接转变为气态；泄漏孔径越大，管道泄漏时间越短，管内介质温度所能达到的最低值更低；N₂的存在缩短了管道泄漏的时间，提高了管内介质的最低温度，且N₂含量越高，该最低温度越高。此外基于管道泄漏时间的自保持性，得出了不同泄漏孔径和起始压力条件下管内压力随泄漏时间变化的经验公式。

关键词: 管道泄漏, 超临界二氧化碳, 压力响应, 最低温度, 杂质